This invention relates to single disk cartridges for use in computer peripheral equipment and in one important aspect to the means in a disk cartridge for releasably retaining a bottom cover of a disk cartridge against a top cover of the disk cartridge.
Typically, such a disk cartridge includes a disk assembly consisting of a single recording disk supported on a hub, which disk assembly is enclosed in a protective top cover having an aperture affording access to one end of the hub; and a pivotably mounted handle on the side of the top cover opposite the aperture. The handle either is permanently coupled, or can be coupled by engagement of a coupling mechanism activated via a thumb-operated slide on the handle, to structure in the cartridge for moving the disk assembly axially away from the aperture to a position adjacent the wall of the top cover opposite the aperture when the handle is moved to a raised position, and for affording movement of the disk assembly axially toward the aperture and rotation of the disk assembly within the top cover when the handle is moved to a lowered position. Such movement of the disk assembly is used in two ways. First, it is used in loading or unloading the disk cartridge from a disk drive machine. The disk assembly is moved adjacent the wall of the top cover opposite the aperture by raising the handle before the cartridge is inserted in the disk drive machine. After the cartridge is inserted, the handle is lowered, which allows the hub of the disk assembly to engage a magnetic chuck through the aperture in the top cover of the disk cartridge so that the disk assembly can be rotated via the chuck and heads in the machine can read and write magnetically encoded information on the disk assembly. To subsequently remove the disk cartridge from the disk drive machine the disk assembly is again moved adjacent the wall of the top cover opposite the aperture by raising the handle, which, because the top cover is supported in a fixed position relative to the chuck, pulls the disk assembly away from the magnetic chuck so that the disk cartridge can be lifted out of the machine.
Secondly, it is used for releasing a bottom cover which may be secured to the top cover, which bottom cover is used during storage of the disk cartridge to restrict dust from entering the disk cartridge. The bottom cover has a ring of permanent magnets disposed adjacent the aperture when the bottom cover is in place to magnetically engage the hub of the disk assembly. The bottom cover is removed by moving the disk assembly adjacent the wall of the top cover opposite the aperture by raising the handle, which, because the top cover remains in a fixed position relative to the bottom cover, moves the disk assembly away from the permanent magnets, whereupon the bottom cover can be removed.
While these means for releasably attaching the bottom cover are effective, they are more expensive than may be desired because of the cost of the permanent magnets that attach the bottom cover to the hub. Also, the coupling mechanism used in some disk cartridges is more complex and expensive than may be desired, whereas with the disk cartridges that do not provide this coupling mechanism, a user cannot raise the handle to carry the disk cartridge around without releasing the bottom cover.
Additionally, the attached bottom cover provides little protection against damage to the disk assembly if the cartridge is dropped on its edge. Under such circumstances the hub can slide sideways on the magnets in the bottom cover, ride up and tip over a centering pin, and impact against the top cover.